Chemical mechanical polishing (“CMP”) is a semiconductor wafer planarizing and/or polishing procedure widely used in the fabrication of semiconductor wafers. As the name implies, there are two components to the process: chemical and mechanical polishing. Chemical polishing involves the introduction of chemicals that dissolve imperfections and impurities present upon the wafer. Mechanical polishing involves rotating the wafer upon an abrasive pad in order to planarize the wafer.
Generally, the wafers are mounted upside down on a wafer carrier and rotated above a polishing pad sitting on a platen, which is also rotated. Typically, a slurry containing both chemicals and abrasives is introduced upon the pad via a slurry delivery system that includes a slurry pump. If for some reason the slurry pump malfunctions then slurry may not be adequately delivered to the polishing pad, which may cause problems with the wafers that are being polished, such as severe scratching, inadequate polishing, or incorrect wafer thickness after the CMP process.